Medical instruments used in hospital operating room environments must be maintained in a sterile condition prior to and during surgery. Sterilization of these instruments is most commonly achieved by thermal treatment in an autoclave in which the instruments are subjected to a steam flow in an enclosed chamber at an elevated temperature and pressure for a predetermined period of time. Other sterilization procedures include bactericidal chemical washes and exposure to various types of light radiation, nuclear radiation, and charged-particle radiation. Traditional medical instruments are, of course, fabricated from materials that permit repeated sterilization over a long period of time without deteroriation. As medical instrument technology has advanced, more instruments are being developed which utilize electrical and electronic components. An example of one such device is a hand-held electrical drill that receives its operating power from detachable rechargeable battery packs. While power tools of this type provide obvious advantages to a surgeon during an operation, a practical problem results from the need to sterilize the tool and/or to use sterilizable portable tools.
It is generally considered impracticable to provide a sterilized rechargeable battery or battery pack in an operating room context since the batteries are often-times fatally degraded during thermal sterilization, and other sterilization techniques, such as radiation sterilization, are not practical in an operating room environment. In addition, it is also considered impracticable to prepare or otherwise provide charged sterilized batteries and store them in their sterilized state for subsequent use in the operating room since the shelf life of the batteries is both variable and of comparatively short duration.